Cementation of aemoe plates



4 Sheets-+Sheet 1.

(No Model.)

H. SG-HNEIDER. I GEMENTATION 0P ARMOR PLATES.

Patented Dec. 3, 1895.

(No Model.) 4 SheetS -Sheet 2.

H. SCHNEIDER. GEMENTATION OF ARMOR PLATES.

No. 550,727. Patentefl'De'c. 3, 1895.

- ANDREW BARANANL PHOTO-HMO. WASNINGTON. EC

(No Model.) 4 Sheets-Sheet 3 H. SCHNEIDER. GEMBNTATION 0F ARMOB. PLATES.

No. 550,727. Patented Dec. 3, 1895.

(No Model.) 4 sssssss Sheet 4.

H. SCHNEIDER. UEMENTATION 0F ARMOR PLATES.

No. 550,727. Patented Dec. 3, 1895.

9m N W 7 lJNirnn drains PATENT FFlCE.

HENRI SCHNEIDER, OF OREUZOT, FRANCE.

CEMENTATION OF ARMOR-PLATES.

SPECIFICATION forming part of Letters Patent No. 550,727, dated December3, 1895.

Application filed September 4:, 1893. Serial No. 484,777. (No model.)Patented in France March 15, 1893, No. 228,637.

To all whom it may concern:

Be it known that I, HENRI SCHNEIDER, a resident of Creuzot, Departmentof Saone et Loire, France, have invented a new and useful Improvement inCementation of Armor- Plates, (for which I have obtained a Frenchpatent, No. 228,637, dated March 15, 1893,) which improvement is fullyset forth in the following specification.

The present invention relates to a process for the cementation orsupercarbonization of one of the surfaces of armor-plates, which,combined with an energetic tempering, aug- 'ments the hardness of theplate and its resistance to penetration of projectiles.

The invention relates particularly to a process in which gaseouscementing agents are employed, whereby a more rapid cementation may beobtained at equal temperature than where solid carbonaceous materialsare employed. The gaseous agents may be obtained either fromdistillation of coal or of mineral oils, and their action may beimproved by the addition of a certain quantity of ammoniagas. Theinvention has for its object to apply this gaseous cementation in apractical and efficient manner to armor-plate, which, on account of thegreat size of the mass, the high temperature employed, and the long duration of the treatment, requires that the operation be conducted in aspecial manner and under special conditions in order to obtain practicalresults; and the present invention is broadly distinguished from theprocesses heretofore proposed for converting iron into steel in closedretorts by means of hydrocarbon gases, which processes, as is wellknown, are rather theoretical than practical.

According to my invention the surface of the plate (or the surfaces ofthe plates, if two be treated simultaneously) forms part of the wall ofthe chamber or inclosure in which the cementation is carried on. Thechamber is completed by walls of suitable materials, as hereinafterspecified, so joined to or combined with the surface of the plate orplates to be treated as to make joints which will not be affected by theexpansion and contraction of the plates under the great changes oftemperature to which they are exposed. This portion of the operation isessential to the at tainment of successful results, because theexistence of openings in the joints causes waste of gas and interfereswith the maintenance of the proper pressure, and, chiefly, because theentrance of the flame of the furnace into the cementatiornchamber wouldproduce oxidation and defeat the object of the invention. v

Means for maintaining unobstructed inlets and outlets for the gaseouscementation agents are also an essential feature of the invention.Without such means the carbon would deposit from the gas in the pipesand arrest the process. The exit pipe is carried through the furnace anddischarges outside the same. This is specially usefulbecause its gas canbe ignited as it issues from the discharge-pipe, and the appearance ofthe flame affords an indication whereby the progress of the operationcan be determined, and from which the pressure of the gas and theduration of the treatment can be regulated.

The process may be carried on in an ordinary furnace with fixed ormovable body, as may be most convenient.

The invention will be more fully explained in connection with theaccompanying drawings, in which Figure 1 represents in vertical sectiona reverberatory furnace in which a plate A is in course of treatment.Figs. 2 and 3 are details in section and elevation, respectively, of thearrangement of supply and exit pipes, that shown in Fig. 3 being for usewith oil. Fig. at illustrates an arrangement for treating two platessimultaneously. Figs. 5, 6, and 7 illustrate other dispositions of theplate. Figs. 8, 9, and 10 are sectional views representing apparatus fortreating the plates in a vertical position.

In Fig. 1 F represents the hearth of the furnace, V the arch, and C thechimney. The upper face a b of the plate A is that to be cemented, and,as shown throughout the drawings, this plate forms part of thecementation-chainber B. B is a cover, of cast-iron, sheet'iron,cast-steel, or refractory brick, in which is conducted the carburetedgas by means of the pipe T. To prevent theescape of the gas between thecover B and the plate, I a joint of sand is made all around, asindicated by n a, being maintained by a framework an m or simply byrefractory earth.

The

' obstructed.

cover 13 is so combined with the plate A that the great expansion andcontraction of the latter under the changes of temperature to which itis exposed may freely take place without opening the joints, and thisarrangement is maintained in all the dispositions of the plate orplates.

Fig. 2 shows in detail the arrangement of the pipes for the admission ofthe gas. It is known that upon making a hydrocarburet pass into a tubeheated to red heat decomposition is produced, giving rise to a depositof carbon. To avoid this deposit, which would soon obstruct the pipe 25,the latter is proteeted by a circulation of water in the jacket T. Thewater enters by a pipe 13 and departs by pipe 1). To be sure that thegas is not lacking, it is introduced in slight excess, the excess beingallowed to escape by a pipe t. c and e are the plugs which permit ofverifying the fact that the tubes 15 and t are not d d are the pointswhere the gas commences to decompose and to deposit carbon. In case ofnecessity the tubes 25 t are cleared out by means of a red bywithdrawing the stoppers c c. The gas and water pipes are provided withsuitable cocks 76.

Fig. 3 shows a modification in which, instead of gas, mineral oil isemployed, this being introduced drop by drop. On coming within the coverB, which has been brought to a red heat, the oil is decomposed andfurnishes the carbonated gas serving for cementation. An acceleration ofthe cementation is obtained by mixing a small quantity of ammonia-gaswith the hydrocarbon gas.

In Fig. 4 the two plates A A are arranged to have their opposite facessimultaneously treated. The upper plate A rests upon a rectangular framem, which may be of refractory material, such as fire-brick. The weightof the plate makes a tight joint, and, as will be observed, thedisposition admits of the expansion and contraction of the plateswithout liability of making openings or leaks from the chamber B intothe furnace. The upper plate in this instance takes the place of themovable cover.

Figs. 5, 6, and 7 represent other dispositions for obtaining an evenheating. In Fig. 5 the plate A is entirely within the inclosure formedby the cover B. The latter rests at its edge upon a flanged base-plateP, the space between the cover B and flange 19 being filled with sand toinsure a gas-tight joint. In this case the surfaces of the plate Awhichare not to be cemented must be covered with refractory earth or otherrefractory material, as represented by g. In Fig. 6 the plate is placedon little walls of brick m m, which, with the body of the furnace andthe surface of the plate, constitute the gas-cha1nber B. In Fig. 7 thechamber is formed by a plane plate D, carried on little walls m, offire-brick, and on additional supports 0, which may also be offire-brick or other suitable material.

Figs. 8, 9, and 10 represent vertical arran gements of the plates. .InFig. 9 the principal parts of the furnace are shown, F F being thehearths, and M a movable cover. The two plates A A are arranged in amanner analogous to the arrangement shown in Fig. 4, the space betweenthe edges of the plates being closed by refractory clay q or by othersuitable material. In Figs. 9 and 10 a single plate is treated, usebeing made of a metallic cover B to complete the chamber 13, whereof thesurface of the plate A forms one of the walls. In Fig. 10 the coverrests 011 a flanged base-plate P, as in Fig. 5.

lVhichever one of the apparatus may be adopted, the operation will beconducted in the same manner. The plate will be maintained at red heatin contact with the gaseous cementing agents for a longer or shortertime, according to the thickness of the cementation which it is desiredto obtain. In each case it will be-of advantage to employ a temperatureas high as possible, but it will be limited to the temperature at whichthe metal of the plate would be altered. For soft steel this temperaturewill be the clear yellow. For hard steel of about 0. per cent. of carbonthe clear cherry should not be exceeded. The intermediary steels will beheated to the intermediary colors. As an instance we will say that aplate of thirty centimeters of thickness in steel of medium hardness (O.0.45) ought to be maintained at yellow oxidation during seventy-twohours to obtain a decreasing cementation of about twenty millimeters ofthickness. Once the desired degree of cementation is obtained, the platemay be left to cool in the furnace either completely or only to thecolor suitable for tempering. The gas will be left in contact with thecemented face until the temperature descends to a dull red.

. The plate might be also withdrawn from the j furnace and left to cool,taking care to preserve the cemented part a Z) from contact with the airuntil it cools to a somber red heat.

Having fully described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. The described process of cementation of plates to be carbonized onone side only, said process consisting in forming in a furnace agas-tight chamber or inclosure having the surface or surfaces to becemented for part of the wall thereof, the chamber being completed bymeans which admit of expansion of the plates without forming openingsfrom the chamber to the furnace, heating the plate or plates, andadmitting to said chamber gaseous cementing agents, substantially as setforth.

2. The combination with a furnace for cementation of armor plates, of aremovable cover applied to the sideof the plate to be treated andforming with the surface ofsaid plate a closed gas-tight chamber, andpipes for conveyin g gaseous cementing agents to and from said chamber,substantially as described.

3. The combination with the cementation furnace, and with the cover ordevice forming part of a gas-tight cementation chamber jacketsurrounding said pipes and provided in said furnace, of supply and exitpipes com- With Water inlets and outlets, substantially as municatingwith said cementation chamber described.

and provided with means for regulating" the In testimony whereof I havesigned this 15 5 supply and pressure, and With means forprespecification in the presence of tWo subscribventing deposits ofcarbon in said pipes, subing Witnesses.

stantially as described.

4. The combination With the cover or device adapted to form part ofacementation cham- Witnesses: 10 her, of gas inlet and outlet pipesconnected CHARLES LAUREAU,

with said cover or device, and atube or water HIPPOLYTE OLIVIER.

HENRI SCHNEIDER.

